EVTripPlanner vs Model S planning and range assurance

Apologies if this has been discussed to death, but I couldn't find anything definitive with a reasonable amount of searching..

What's the general consensus on the accuracy of EVTripPlanner in comparison to the in-car estimation in the Model S? I ask because the one and only 'long' trip I've done so far differed quite considerably between the two. The car estimates pre-trip of percentage remaining at destination and and the end of the round trip came in within a percent or two (and I didn't drive entirely at the 'proper' speed for the roads that it would have used in the calculation).

The actual usage reported was just over 20kWh in each direction. Yet the planning I'd done with EVTripPlanner for the same route had indicated only about 17kWh in each direction, a pretty substantial difference in percentage terms. As far as I'm aware I accounted for all the variables in EVTP correctly, yet the result was not as accurate as I'd expected it to be from what I'd read about it, and far enough off the actual usage to be a worry if I tried to use it at all close to range limits.

Have others found this at all? Is there something I'm missing perhaps?

I mostly do long trips and have found the car more accurate than EVTrip Planner

Click to expand...

Thanks Michael. In which direction did you tend to see EVTP err? Because from what I can find written by others they tend to say it is conservative and they actually use less than it predicts, but still pretty close on actual kWh usage. My experience was the opposite, with it significantly underestimating usage.

I've used EV Trip Planner whenever we go on a trip (probably time for me to make another donation to the education fund of the student who wrote it ).

I haven't bothered to record how much "out" it might be; I can only say that we haven't had any problems whatsoever. I set up EVTP with my model, tires, weight (2 people plus luggage), and usually the 1.05 speed multiplier. I generally drive at slightly over whatever the speed limit is (5-8km/hr). Oops did I just say that? I mean, officer, right AT the speed limit. Yeah, that's it.

So in trip planning I note the RM that EVTP predicts for any particular leg, then when charging pre-leg I just add 30-50 km (or miles if travelling US) as a comfort buffer. Of course, often with superchargers the car is ready before we are with our fiddling around so I can end up with more charge than I actually need. For the last several trips, the lowest I've ended up with, pulling into the charging station, has been about 20km. And while I check RM against distance to destination throughout the drive (and now use the new trip % estimator), there's no anxiety. And I'm not afraid to boot it if the traffic situation warrants (to avoid getting bunched, to get out of the way of a speeder while I'm cruise-control-passing someone, etc).

Btw, the primary reason I still leg plan is for us (the humans), ensuring our total daily planned mileage and overall driving day isn't more than we physically want to handle (600-700km per day).

Thanks Michael. In which direction did you tend to see EVTP err? Because from what I can find written by others they tend to say it is conservative and they actually use less than it predicts, but still pretty close on actual kWh usage. My experience was the opposite, with it significantly underestimating usage.

Click to expand...

I have used EVTP a few times when temps were warmer and it was pretty accurate. I have noted somewhat higher usage since the cold weather arrived, particularly if you don't use range mode. I'm going up to the Southern Highlands on Friday, Ill do an EVTP estimate and compare to my actual and post it.

Thanks Michael. In which direction did you tend to see EVTP err? Because from what I can find written by others they tend to say it is conservative and they actually use less than it predicts, but still pretty close on actual kWh usage. My experience was the opposite, with it significantly underestimating usage.

I have used both and have found the biggest difference to be real time consumption updates available in the Model S trip planner. On one particular trip between Superchargers, I drove faster than had been originally planned in the EV Trip planner. The MS showed rated range remaining at the next SC to be lower of course. I adjusted my speed and sure enough the rated remaining range adjusted accordingly after some time. It is handy to show if I am on track with energy consumption or not.

One of the problems might be that if you drive late in the day as it cools down the car may need to put more energy into battery heating. I may leave Melbourne late afternoon when its 16 degrees and arrive in NE Victoria when its 2 degrees after sunset. EV Trip Planner allows me to enter only one temperature value so that will always limit calculation accuracy.

Have just driven from Sydney to Southern Highlands. It was 15 deg C when we left and 5 when we arrived.
I drove very close to the speed limits all the way with Range Mode turned on.
Trip view calculated 210Wh/Km and the car told me it had used 207Wh/Km.
The settings I used was 10 deg C, 150kg payload (2 people) and speed factor 1.

The calculation from the Model S was quite good on a 6000 mi road trip that I just completed. The biggest problem is the navigation would often try to route me back to Superchargers already visited and many miles behind.

Have just driven from Sydney to Southern Highlands. It was 15 deg C when we left and 5 when we arrived.
I drove very close to the speed limits all the way with Range Mode turned on.
Trip view calculated 210Wh/Km and the car told me it had used 207Wh/Km.
The settings I used was 10 deg C, 150kg payload (2 people) and speed factor 1.

Click to expand...

Interesting meloccom, thanks. Makes me start to wonder why it was so far off for me. True, it was first time in the car for a few people and so there were one or two brief floorings of the pedal, but no more than that. I guess it's possible that they chewed up more than I expected but it seems unlikely. Plus I'm pretty sure they were mainly on the outward leg, not the return trip, and both legs came in about the same power usage. I guess I'll see how it goes on subsequent trips.

Ok so did another trip today and took note of the car's usage figures for the main out and return legs. Comparing to EVTP's predicted usage with criteria set as close to reality as I could get I saw the following:

Considerably better than the last time, but still optimistic and so erring in the opposite direction to most people's experiences. The fact that it got closer to the car's reported usage though makes me wonder if the car is slowly getting more accurate in determining usage as the battery goes through more charge/discharge cycles. Doesn't make much sense intuitively though, unless they're estimating current drain from system parameters rather than directly measuring it (which should give exact energy usage regardless of battery capacity numbers).

If this is as close as it gets though it's still pretty good, and I can usefully use EVTP to plan longer trips, which is the main thing.

I haven't used the onboard energy calc for any reasonable distance trip - but on short trips I'm confused as to which line represents the predicted vs actual usage. Is the prediction the green or the grey line? On a short trip the two are so close together that you can't easily distinguish which is which..

I've found the car's energy planning to be very accurate. EVTP appears to have an issue with hills in that it overestimates how much you'll use going up and underestimates how much you'll get coming down.

I haven't used the onboard energy calc for any reasonable distance trip - but on short trips I'm confused as to which line represents the predicted vs actual usage. Is the prediction the green or the grey line? On a short trip the two are so close together that you can't easily distinguish which is which..

Click to expand...

The green line is what you are achieving. The grey line is the original projection. The confusing part is that when you start your trip, only the green line shows.

Both underestimate on my trips in Wyoming, they don't account for the extreme winds in south part of Wyoming. It can eat a 30% or more in range on a 5 hour trip to colorado for me. EV Trip planner kind of has a chart. It would be cool if it could check the road conditions, wind, weather and speed limit from the state websites like Wyoming Travel Information Map and facter that in.

I've found the car's energy planning to be very accurate. EVTP appears to have an issue with hills in that it overestimates how much you'll use going up and underestimates how much you'll get coming down.

Click to expand...

Yes so far the three trips I've done I think the car's projection for remaining percentage at least has been pretty close at the end. On all three so far though EVTP has continued to *under* estimate the usage, by between 6% and 20%. Yesterday's trip was about 9% off. Still puzzling since the overwhelming weight of reports from others are that EVTP is pessimistic if anything and they generally achieve better than its projections.

It would be great if the car included a planning mode rather than just the real time estimation from current location and SoC. Quite likely to come at some point I guess, it would be a relatively simple addition for them.